diff --git a/vm/os-windows-nt.c b/vm/os-windows-nt.c
index da54b794d1..e425b6b94c 100755
--- a/vm/os-windows-nt.c
+++ b/vm/os-windows-nt.c
@@ -84,9 +84,11 @@ long exception_handler(PEXCEPTION_POINTERS pe)
 
 void c_to_factor_toplevel(CELL quot)
 {
-	AddVectoredExceptionHandler(0, (void*)exception_handler);
+	if(!AddVectoredExceptionHandler(0, (void*)exception_handler))
+		fatal_error("AddVectoredExceptionHandler failed", 0);
 	c_to_factor(quot);
-	RemoveVectoredExceptionHandler((void*)exception_handler);
+	if(!RemoveVectoredExceptionHandler((void*)exception_handler))
+		fatal_error("RemoveVectoredExceptionHandler failed", 0);
 }
 
 void open_console(void)